Longitudinal spin-fluctuations and superconductivity in ferromagnetic ZrZn₂ from ab initio calculations

The recent discovery of superconductivity coexisting with weak itinerant ferromagnetism in the $d$-electron intermetallic compound ZrZn$_{2}$ strongly suggests spin-fluctuation mediated superconductivity. {\it Ab initio} electronic structure calculations of the Fermi surface and generalized susceptibilities are performed to investigate the viability of longitudinal spin-fluctuation-induced spin-triplet superconductivity in the ferromagnetic state. The critical temperature is estimated to be of the order of 1 K. Additionally, it is shown that in spite of a strong electron-phonon coupling ($\lambda_{ph}=0.7$), conventional s-wave superconductivity is inhibited by the presence of strong spin-fluctuations.